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I used a 1.5v alkaline battery in my MR-4 and the meter always indicated the voltage was slightly off. Not wishing to muck about with the innards of the meter, I just lived with it.

Reading on Ken Rockwell's site about the Wein 1.35v replacement for the original mercury battery, I ordered one, popped it in, and now the meter needle sits right on top of the silver dot, indicating proper battery power.

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I just got a nice Leicameter MR 4 No 94991 for my M3. How do I know which battery I need? I have both an EPX625G (Alkaline 1.5 V) and a Wine Cell MRB625 (1.35 V).

I read that originally the Leicameter was designed for the Mallory PX 625 1.35 V battery, but later models were adjusted for 1.5 V Alkaline. How do I know which model is mine?

Can you please help?

Thank you in advance.

Regards

Swiss leica fan

"In helping my friend secure an MR-4 for his non-metered M's, I've gotten hold of several of them in working/accurate condition and discovered something interesting:

Checking the readings at the low, mid and high ends of the brightness range, I have found no variation between the following (voltages tested on a meter):

a new (never used) PX625 1.3V Mercury battery

a new PX625-A 1.5V Alkaline battery

a new MS76 1.55v Silver-Oxide battery in a CRIS MR9 1.3v adaptor

a new MS76 1.55v Silver-Oxide battery in a washer-spacer (left over from a Wein cell).

I did not have the same results when I tried this with a Leicaflex SL, M5 or CL, all of which required compensation with a 1.5v and then would still not read accurately at both ends of the brightness range.

Could it be that the MR-4, made by Metrawatt, has a built-in voltage regulator that nobody knows about? I'm reluctant to open these meters since I don't own them, and wouldn't know what I was looking at if I did. Just curious if anybody else has checked an MR4 with different battery types and found the same thing. I don't mean the readings are close, they're *identical*. BTW for using the MR9 adaptor I would recommend a 386 vs an MS76 because the latter is thicker and pushes the battery door open a little--and those battery doors don't look like they're too strong"

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The Wein cell is your best choice. Though it's still not guaranteed to make it work. I got a Wein cell, and it worked fine (I used it in another camera and the meter readings were correct), but turns out my MR4 needs adjusting. I just keep it on my shelf. Too much of a hassle to send it out and get it fixed. I'd suggest an alternative meter.

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Thank you for all your helpful comments. Looks like this is not an easy issue. As I will leave today for a two weeks trip to Italy, I better bring my Gossen Multisix meter and do some 1.5 V vs. 1.35 V experiments afterwards.

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I use the MR-9 in the MR4 (actually in a few of them). It can be touchy to get the battery in just the right position, but once it makes good contact they work fine. The Wein cell works well also. There is also another adapter made which takes a zinc-air hearing aid battery. All three are good solutions.

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Can you be specific about the problem with the MR-9? Which battery are you using in it? This thread mentions two, a "386" and an "MS76". Is the problem the contact of the battery with the MR-9, or the contact of the whole assembly, i.e., MR-9 with battery in it, with the contacts in the battery case of the Leicameter? I've contacted CRIS, and they say that Kanto, the Japanese manufacturer of the MR-9, says that the Leicameter needs a modification; however, CRIS can't tell me any more about the modification, and Kanto doesn't answer my emails. It would help to know whether the modification is mechanical or electronic.

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I use a 386 in the MR-9. The 76 and 44 batteries are too thick. Sometimes when I put in the MR-9 with battery the meter has no response, until I open the battery compartment and make sure the battery is in perfectly flat, so it looks to me like it's a battery fit issue.

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It's probably some kind of measurement or spacing issue... I use a different adapter, the one sold by Dutchman Frans de Gruijter (author of the PDF linked above by Xmas) and it works nicely with the MR. This adapter uses a diode to get down the voltage of a SR44 silver cell to 1.35V. It's also quite a bit cheaper than the CRIS adapter. However, it doesn't work with my Gossen Sixtar (aka Gossen Super Pilot), because of the design of the Gossen's battery chamber. You can also use one of the mechanical adapters sold on Ebay together with an zinc-air hearing aid battery (675 type).

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real world solution (s); If you have or can get a wein cell, you can replace the cell itself with a 675 zinc/air hearing aid battery. Use a pair of pliers like a spanner the push the "ring" off the exhausted wein cell and insert a new 675 and voila! you're good. Better yet is use a readily available PX625A alkaline cell as a direct replacement for the original. It'll work fine. This was suggested to me by reputable repairperson and I've used it for several years now. Just do it, it works. cheers!

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"In helping my friend secure an MR-4 for his non-metered M's, I've gotten hold of several of them in working/accurate condition and discovered something interesting:

Checking the readings at the low, mid and high ends of the brightness range, I have found no variation between the following (voltages tested on a meter):

a new (never used) PX625 1.3V Mercury battery

a new PX625-A 1.5V Alkaline battery

a new MS76 1.55v Silver-Oxide battery in a CRIS MR9 1.3v adaptor

a new MS76 1.55v Silver-Oxide battery in a washer-spacer (left over from a Wein cell).

I did not have the same results when I tried this with a Leicaflex SL, M5 or CL, all of which required compensation with a 1.5v and then would still not read accurately at both ends of the brightness range.

Could it be that the MR-4, made by Metrawatt, has a built-in voltage regulator that nobody knows about? I'm reluctant to open these meters since I don't own them, and wouldn't know what I was looking at if I did. Just curious if anybody else has checked an MR4 with different battery types and found the same thing. I don't mean the readings are close, they're *identical*. BTW for using the MR9 adaptor I would recommend a 386 vs an MS76 because the latter is thicker and pushes the battery door open a little--and those battery doors don't look like they're too strong"